Another thing that did was the reflections on the car in the left. They aren't really realistic...completely, and I don't think games have started using antialised raytrace yet, so its easy to tell when its using it. It doesn't form around the car in the right way if you get me.

The graphics are impressive though, but in another way, there not really.
PGR3 was meant to be impressive graphically (and in one sense it is), but in another sense, its not. Some cars lack alot of detail, with only the reflections making up for it...just, but the scenes add to alot of the realism in that game, and plus all the pixel effects added like motion blur, depth of field (something new), etc.